Para substituted alpha-phenylpropionic acids are known to have anti-inflammatory, analgesic and antipyretic properties comparable or superior to those of aspirin, which properties make these compounds particularly useful in the treatment of rheumatoid arthritis.
The compound Ibuprofen, or 2-(4-isobutylphenyl) propionic acid, has gained wide acceptance as a therapeutic agent for the treatment of rheumatoid arthritis to relieve pain, reduce fever, swelling and tenderness. These compounds and their uses are described for example in British Pat. No. 971,700 and corresponding U.S. Pat. Nos. 3,228,831 and 3,385,886 and in Adams et al. Arch. Pharmacodyn. Ther. 178: page 115 (1969), the disclosures of which are incorporated by reference. The foregoing disclosures also set out several processes for the preparation of para substituted, alpha-phenylpropionic acids, which processes are, for the most part, more theoretical than practical and do not lend themselves readily to satisfactory industrial application.
It is, therefore, an object of this invention to provide a novel synthetic route for the preparation of para substituted alpha-phenylpropionic acids which is especially well suited to manufacturing such compounds on an industrial scale and, in particular, a process for manufacturing 2-(4-isobutylphenyl)propionic acid and its pharmaceutically useful salts and derivatives.